Elastance Imaging LLC News – March 2018
December 2018, Bill Timmons, Juve Ormachea (Dr. Parker’s doctoral student), and Ken McCaw traveled to Dr. Richard Barr’s clinic in Youngstown, OH, where we performed a second set of patient tests with Elastance Imaging’s current research prototype imaging software and hardware system. (Dr Barr is one of the world’s leading experts in clinical elastography and a practicing radiologist.) Tests included liver, kidney, Achilles tendon and breast. We were successful in reaching frequencies up to 900hz in liver and 1200hz in breast, which is far above any known system in the world. The higher the frequency, the greater the resolution and specificity.
Southwoods Imaging, Boardman, Ohio
Bill standing next to the “Quadratactile Resonator”
for deep tissue elastography
Dr. Barr made it clear from the first hour of testing that he wanted to see if our method could go head-to-head with the current front-runner in elastography, ARFI, with which Dr. Barr and Juve are both experts. For some applications, ARFI works very well; however, one of its weaknesses is depth, making it ineffective to see much, if any, of the liver in an obese person. Because ARFI is only effective to about 6cm (2.36”), we had set our machine to see 4cm beyond that, to a 10cm depth. Dr. Barr immediately noticed, and challenged us to see beyond that by at least 4cm, to a depth of at least 14cm. We were now entering uncharted territory. After adjusting our machine settings and validating the changes, we demonstrated we could see not only through the entire liver, but beyond it and through the entire kidney, out to 17cm!
Juve reconstructing an elastography image in one of Dr. Barr’s exam rooms. To the right of Juve is Ken’s studio amplifier/EQ rack and Elastance Imaging’s portable waveform generator, which eventually will be miniaturized to fit into a small box packaged with the Quadratactile Resonator.
The following two slides (from the live testing with Dr. Barr) show a kidney scan sequence and a deep liver scan. The kidney scan is comprised of three sequential single frequency scans, and the deep liver scan was obtained using a complex, multifrequency vibration pattern. With ARFI-based commercial elastography scanners, kidney is very noisy and difficult to image, and deep liver scans, especially in obese, are impossible. Both slides below therefore represent significant advancements in the field, and demonstrate that our technology succeeds where ARFI fails. Both advancements should have significant clinical utility.
Reverberant Elastography Scans of Kidney: Kidney elastography is extremely difficult for traditional ARFI-based elastography due to echogenicity of the fibrous kidney capsule and anisotropy of the tissue, resulting in reverberations that corrupt normal image reconstructions. Elastance Imaging instead utilizes the reverberations to calculate elastography. The above three, single-tone scans were performed sequentially on a live subject using a C4-2 probe scanning a full 17 cm depth. In each, the b-mode ultrasound image is shown on the left, and again on the right with elastography (stiffness) superimposed using a standard jet colormap to indicate shear wave speed.
Multi-Frequency Single Scan of Liver in Obese Subject: Elastography of liver in an obese individual is extremely difficult to obtain using traditional ARFI-based elastography due to its 6 cm depth limitation. Elastance Imaging utilizes external acoustic vibrators to induce deep tissue reverberant shear wave fields in the body, enabling full depth elastography. The above single scan utilized a multi-frequency (multi-tone) reverberant shear wave field on a live subject using a C4-2 probe scanning 17 cm deep for 0.25 seconds. Each frequency in the multi-tone complex is displayed separately. In each, the b-mode ultrasound image is shown on the left, and again on the right with elastography (stiffness) superimposed using a standard jet colormap to indicate shear wave speed. Note the increasing stiffness with frequency, which is predicted for viscoelastic soft tissues. The wide range in frequencies in the complex waveform provides high confidence in Elastance Imaging’s viscosity estimates.
In early March 2019, after being challenged by a former manager from the Siemens company to prove how high we could go in frequency for breast imaging, Ken built a new apparatus and we were able to reach 4,000hz in a breast patient, which now places our technology within the specificity range of mammography… without the discomfort of current mammography machines and with no ionizing radiation. Our systems are non-invasive and should be inexpensive compared to MRI and other methods..
Disclaimers: The Quadratactile Resonator and Elastance Imaging LLC’s elastography system is for research use only. All human data was obtained by Dr. Barr and his staff under an IRB approved protocol. FDA approval will be required by ultrasound manufacturers before offering the system for sale for use with patients. At this time, it is not available for commercial sale.